Stretch laminates are often used in disposable absorbent articles. For example, stretch laminates can be utilized in leg regions and waist regions of a disposable absorbent diaper, thereby allowing the disposable absorbent diaper to extend and contract about the leg regions and the waist region. The capability to extend and contract about the leg regions and the waist can provide improved fit for the disposable absorbent diaper with a wide range of wearers.
Conventional stretch laminates typically comprise a pair of nonwovens and an elastic film sandwiched in between the pair of nonwovens. Generally, the two nonwoven materials are attached to the elastic film via an adhesive.
Convention stretch laminates typically comprise multiple regions of adhesive application. For example, some conventional stretch laminates may comprise a pair of tack down regions disposed adjacent to the ends of the laminate. Additionally, some conventional stretch laminates will further comprise an activation region disposed between the tack down regions.
In general conventional stretch laminates are subjected to a nipping process and then to a mechanical activation process. The nipping process typically compresses the pair of nonwovens and the elastic film together causing the adhesive to penetrate into the interstices of the nonwovens.
Downstream of the nipping process, the mechanical activation process generally involves meshing the conventional stretch laminate between sets of teeth. Typically, during the mechanical activation process, the activation region of the stretch laminate is meshed between the teeth while the tack down regions are generally not significantly meshed between the teeth. Because conventional stretch laminates are intermeshed between the teeth of the activation rolls, the nonwoven materials are permanently elongated at least to a certain degree, so that upon release of the applied tensile forces, the stretch laminate generally will not fully return to its original undistorted configuration.
The mechanical activation process is often performed at high speeds which may cause the stretch laminate to experience high strain rates during the mechanical activation process. Moreover, in order to provide the stretch laminate with greater extensibility, the stretch laminate may be exposed to high percentages of strain which can also lead to higher strain rates during mechanical activation. Unfortunately, higher strain rates are typically associated with higher defect levels.
Many stretch laminates can incur defects from the mechanical activation process, in part, because of the high strain rates experienced during the mechanical activation process. Many of the defects are structural in nature. For example, an elastic film which undergoes the mechanical activation process may experience defects such as holes which may reduce the structural integrity of the elastic film.
Consequently, a method is needed for producing a stretch laminate which exhibits reduced defects from a mechanical activation process.